1. Field of the Invention
The present invention relates generally to electrical switching apparatus, and in particular to an improved arrangement for securing a contact plate and screw-type electrical contact in the housing of such an apparatus.
2. Description of the Prior Art
Arrangements for securing electrical contacts and contact plates of the above-described type in the housing of an electric switching apparatus by means of a locking member disposed transversely with respect to the direction of insertion of the contact plate and contact into the housing of the apparatus are generally known in the art. In one known arrangement of this type, a cutout having a T-shaped cross section is provided in a wall of the apparatus housing. A contact plate having a tapered middle portion is inserted through the upper part, i.e., bar, of the T-shape cutout, and the tapered middle portion is then slid downwardly into the vertical part of the T-shape of the cutout and is prevented from moving upwardly back to the upper part of the T-shape by means of a leaf spring disposed in the bar portion of the T-shape. A slot is provided on the side surface of the contact plate facing the leaf spring, and the latter is disposed in this slot and is thereby secured against displacement. The disadvantage of this arrangement, however, is that even if the leaf spring is made relatively thick, a secure seating of the contact plate is not attainable and it is possible for the leaf spring to slide out of the slot during operation of the equipment. To avoid this problem, the leaf spring may be provided with an extension which is simultaneously used as a pressure element for the line to be clamped in the apparatus which contains an aperture through which the clamping screw is disposed. Although it is thus assured that the leaf spring is not lost in the housing when the contact is inserted into the contact plate, it is still possible for the contact plate to loosen, particularly if it is used as a switch contact, and the leaf spring can slide out of the housing slot if the screw contact is removed.